The near U.V. absorption spectra of several aliphatic aldehydes and ketones at 300 K

Absorption cross-sections are reported for acetaldehyde, propionaldehyde, isobutyraldehyde, n-butyraldehyde, acetone, 2-butanone, 2-pentanone, and 3-pentanone at wavelengths greater than 200 nm, a temperature of 300 K, and a spectral resolution of 0.50 nm. In general, the results are in good agreement with previous measurements of the spectra of these molecules, but are of higher precision than past measurements. For acetaldehyde, propionaldehyde, isobutyraldehyde, and acetone the cross-section results are combined with previous experimental measurements of the primary quantum yield for photolysis to estimate photodissociation rate constants for a representative set of atmospheric conditions. For the other four carbonyl compounds, upper limits for the photodissociation rate constant are calculated assuming a primary quantum yield of unity at all wavelengths. For acetaldehyde, photolysis is slow in comparison with reaction with hydroxyl radical. For the larger aldehydes and for acetone, photolysis and reaction with OH radical take place at comparable rates. For larger ketones, if the quantum yields for photolysis are unity, as assumed in our calculations, the rate of loss of the compounds by photodissociation could be important compared to reaction with hydroxyl radical.     

Photochemical production of carbonyl sulfide, carbon disulfide and dimethyl sulfide in a lake water

Photochemical production of carbonyl sulfide(COS),carbon disulfide(CS_2) and dimethyl sulfide(DMS) was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly supersaturated with COS,CS_2 and DMS,with their initial concentrations of 0.91 ± 0.073 nmol/L,0.55 ± 0.071 nmol/L and 0.37 ± 0.062 nmol/L,respectively.The evident photochemical production of COS and CS_2 in the lake water under irradiation of 365 nm and 302 nm indicated that photochemical production of them might be the reason for their supersaturation.The similar dependence of wavelength and oxygen for photochemical production of COS,CS_2 and DMS implied that they might be from the same precursors.The water cage effect was found to favor COS production but inhibit CS_2and DMS formation,indicating that COS photochemical production was mainly from direct degradation of the precursors and the formation of CS_2 and DMS needed intermediates via combination of carbon-centered radicals and sulfur-centered radicals.The above assumptions were further confirmed by simulation experiments with addition of carbonyls and amino acids(cysteine and methionine),and the photochemical formation mechanisms for COS,CS_2 and DMS in water were derived from the investigations.     

华北农村大气PM_(2.5)中水溶性物质化学组成、吸湿性能及光学特征

2013年6月10—25日在河北保定市固城镇运用大流量采样器进行每3小时1次PM_(2.5)样品采集,对其进行有机碳(OC)、元素碳(EC)、水溶性有机碳(WSOC)、水溶性有机氮(WSON)、水溶性总氮(WSTN)、吸湿增长因子、吸光度以及无机离子分析,探讨其浓度、组成、吸湿性能与吸光性的变化特征。结果表明:采样期间固城镇PM_(2.5)中WSON平均浓度为5.0±4.0μg?m~(-3),最高浓度达15μg?m~(-3);污染期WSON为6.9±3.9μg?m~(-3),是清洁期的四倍。整个采样期间WSON与、和呈强线性相关(R~20.89),污染天阳阴离子当量比值F=1.01,清洁天F=1.45,表明污染期颗粒物酸性增强有利于气态有机胺等WSON通过酸碱中和转移到颗粒相。不同相对湿度下水溶性组分的吸湿增长因子(Gf)测量结果显示:[WSOC+WSON]/离子的比值越大,吸湿增长因子越小,表明与无机离子相比,水溶性有机物吸湿性能较低。固城夏季大气PM_(2.5)中WSOC在365 nm波长下质量吸收效率(MAE)均值为0.52 m~2?g~(-1),表明WSOC对PM_(2.5)整体消光效应具有重要贡献。     

Confined placental mosaicism,IUGR, and adverse pregnancy outcome: A controlled retrospective U.K. collaborative survey

In a retrospective collaborative study involving 21 U.K. laboratories and 11775 CVS prenatal diagnostic procedures, a total of 73 cases of confined placental mosaicism (CPM) were identified among the 8004 first-trimester referrals because of advanced maternal age, a previous child with a numerical chromosome abnormality, or a family history of the same. Data were collected on subsequent cytogenetic follow-up and pregnancy outcome for each case and a referral matched control. Comparison with the control population failed to demonstrate a marked increase in adverse pregnancy outcome in the CPM group, but a significant increase in both low and high birth weight infants was recorded. In a parallel study, 7 out of 108 cases, referred for prenatal diagnosis because of ultrasound detection of isolated intrauterine growth retardation (IUGR) in the second or third trimester, were shown to have a chromosome abnormality restricted to the extraembryonic tissues. These included cases of CPM involving trisomy 9 and del(13)(q13), neither of which has previously been reported in association with IUGR.     

Benefits and hazards of new crops: oilseed rape in the U.K.

An agroecosystem contains many interralated components. Change within that system or even within larger systems affects these components. The adoption of a new crop, like many other innovations, may therefore lead to other changes. This paper reports on the changes that can occur in production, protection and pollution as a result of farmers adopting new crops. This pattern of events is examined in more detail in a case study of oilseed rape in the U.K.     

Mitigation costs,distributional effects,and ancillary benefits of carbon policies in the Nordic countries,the U.K., and Ireland

This paper provides a survey of top-downmodelling analyses of carbon (C) abatementmitigation costs, distributional effectsand ancillary benefits in the Nordiccountries, the U.K. and Ireland. Specialemphasis is placed on the effects ofrevenue recycling and tax exemptions.According to the analyses, modestemissions reductions can be met withoutsubstantial costs for the countriesstudied, and a strong double dividend isfound in some analyses. The gross domesticproduct (GDP) or welfare effects are mostlyin the range of –0.4 and 1.2 percent whenC emissions are reduced by 20–30 per cent.Lowest costs are obtained without taxexemptions and with tax revenues used toreduce distortionary taxes. Ancillarybenefits are mostly in the range35–80/MgC^-1, i.e., about the same order ofmagnitude as the mitigation costs.Distributional effects are mostlyregressive, unless the tax revenues aredistributed in lump-sum fashion with equaltransfers to each household.     

The influence of mountain meteorology on precipitation chemistry at low and high elevations of the Colorado Front Range,U.S.A.

We explored the seasonal characteristics in wet deposition chemistry for two sites located at different elevations along the east slope of the Colorado Front Range in Rocky Mountain National Park. Seasonally separated precipitation was stratified into highly concentrated (high salt), dilute (low salt), or acid-dominated precipitation groups. These groups and unstratified precipitation data were related to mean easterly or westerly zonal winds to determine direction of local transport. Strong acid anion associations were also determined for the stratified and unstratified precipitation data sets. We found that strong acid anions, acidity, ammonium, and high salt concentrations originate to the east of Rocky Mountain National Park, and are transported via up-valley funneling winds or convective instability from differential heating of the mountains and the plains to the east. These influence the composition of precipitation at Beaver Meadows, the low elevation site, throughout the year, while their effect on precipitation at Loch Vale, the high elevation site, is felt most strongly during the summer. During the winter, Loch Vale precipitation is very dilute, and occurs in conjunction with westerly winds resulting from the southerly location of the jet stream.     

Sulphate in atmospheric particulate at five sites in Norwich (U.K.): Use of national survey archive filters

Air sample filters from a Local Authority archive have been analyzed for sulphate using XRF. This has allowed an assessment to be made of the spatial distribution of 24-h sulphate concentrations in the city of Norwich in eastern England, over a 9-month period. The overall mean sulphate concentration was 10.4 μg m⁻³, with a range of overall mean values between the sites of 7.7–12.2 μg m⁻³. This spatial variability within the city is similar to the spatial variability between cities found in another previous study. The mean SO²⁻₄/SO₂ and smoke/SO²⁻₄ ratios at the different sites are similar, but there are distinct variations in the overall mean ratios over the measurement period. There appear to be relationships between the SO²⁻₄/SO₂ ratio and temperature and humidity. The ratios are also related to wind direction, with some evidence that a proportion of the SO²⁻₄ in the urban atmosphere of Norwich originates via long-distance transport from the east.     

The estimation of aerial inputs of metals to estuarine waters from point pattern data using an isoplething technique: Severn Estuary,U.K.

The aerial deposition of Cd, Cr, Cu, Ni, Pb and Zn to the tidal surface of the Severn Estuary in southwest Britain was determined using the nonlinear isoplething of point data from 11 bulk-deposition sampling stations operated between January 1989 and March 1990. Previous surveys based on crude spatial bulking of deposition data from coastal sites had generated overestimates of aerial deposition of metals. The distribution of aerial deposition away from the dominant source around Avonmouth was related to weather variables. Down-estuary deposition gradients were steepest in wet westerly on-shore airflows.     

The effect of increased energy prices on the viability of organic agricultural systems on arable farms in the U.K.

Parametric programming was used on a mixed-integer linear programming model of a typical U.K. arable farm to examine the impact of increased energy prices on the viability of organic farming systems. It was found that, although input costs were generally lower with the organic system, the net farm revenue was reduced due to decreased income from crop sales. The organic system, therefore, did not enter the optimal solution. Energy costs per ha with the organic system were 25% lower than with a conventional cropping system, although energy costs per £ of output were 25% higher. A doubling of energy prices in the model led to only a small improvement in the competitive position of the organic system. This model would suggest, therefore, that changing energy costs are unlikely to have a significant impact on the competitive position of organic agricultural systems on arable farms in the U.K.     

Modelling and measurement of the dispersion of radioactive emissions from a nuclear fuel fabrication plant in the U.K.

The ground-level air concentrations of supported and total ²³⁴Th were determined over a period of 1 year at four sites in the vicinity of a nuclear fuel fabrication plant in northwest England. Both supported and unsupported ²³⁴Th were found, with mean monthly concentrations of total ²³⁴Th 13 times those observed at a control site 50 km north of the factory. Bulk deposition rates of total ²³⁴Th were found to be 2–3 times the background values. Analysis of mosses revealed a systematic decrease in supported ²³⁴Th concentrations with distance from the factory, with background values reached at a distance of about 1.5 km. Road dust samples showed a similar decrease in supported ²³⁴Th concentrations with distance, but with significant departures from this trend, possibly being evidence for the mechanical transport of contaminated dust from the factory. A Gaussian plume dispersion model was able to predict 85% of the observed air concentrations within a factor of four, despite large uncertainties in some source parameters.     

美国超级基金法之借鉴

中国的土地污染现状 经过数十年的工业化进程,中国社会经济发展取得了巨大进步.然而在此过程中,也付出了巨大的资源与环境代价.近年经媒体曝光的镉米、血铅等环境事件更让历史遗留的污染问题曝光于公众视野.产生这类问题的原因在于,采矿冶炼、石油化工、皮革制造等产业的快速发展,农业生产中农药化肥的大量使用,以及化学品不当储运和城乡固体废物的不当处置等制造了大量污染场地.     

Quantifying nonuse and indirect economic benefits of impingement & entrainment reductions at U.S. power plants

Monetizing ecological benefits of reducing impingement and entrainment (I&E) at cooling water intake structures presents both ecological and economic challenges. Ecological challenges arise because it is difficult to demonstrate and measure these impacts. Economic challenges arise because of these ecological uncertainties and because many of the potentially affected ecosystem services cannot be valued using traditional methods. Under a recently promulgated U.S. regulation certain power generation and industrial water permit applicants may be required to monetize these “nonuse” benefits. However, stated preference (SP) surveys, the only method available for valuing nonuse services have not seen acceptance by mainstream economists. This paper describes an approach to valuation that incorporates the ecological service function approach advocated by the USEPA Science Advisory Board to characterize impacts. Data and models are used to quantify, to the extent possible, direct and indirect impacts of I&E on ecosystem services. Nonuse values are then estimated by an SP survey that measures respondents’ willingness to pay for reducing I&E. Methods are proposed for calibrating and validating results including identifying the source of nonuse values from commonly ascribed motivations (i.e. existence, bequest, altruistic), considering the role of pre-survey awareness of impacts, and evaluating results in the context of respondent willingness to pay for other nonuse benefits.